Scientists have known for a number of years that certain diseases are associated with particular genes or genetic mutations. Genetic causation, however, accounts for only a portion of the diseases diagnosed in humans. Many diseases appear to be linked in some way to the immune system's response to infectious and environmental agents, but how the immune system plays a role in diseases such as cancer, Alzheimer's, costochondritis, fibromyalgia, lupus, and other diseases is still being determined.
The human genome comprises a total number of 567-588 Ig (immunoglobulin) and TR (T cell receptor) genes (339-354 Ig and 228-234 TR) per haploid genome, localized in the 7 major loci. They comprise 405-418 V, 32 D, 105-109 J and 25-29 C genes. The number of functional Ig and TR genes is 321-353 per haploid genome. They comprise 187-216 V, 28 D, 86-88 J and 20-21 C genes (http://imgt.cines.fr). Through rearrangement of these genes, it has been estimated that approximately 2.5×107 possible antibodies or T cell receptors can be generated.
Although, at the germine level, human beings are capable of generating large numbers of diverse Igs and TRs, the number of available Igs and TRs for a particular individual is actually much smaller due to negative selection during B and T cell development. In some individuals, this process may not remove some of the cells that would cross-react with the body's own tissues, and this may be the cause of some types of autoimmune diseases.
A few diseases to date have been associated with the body's reaction to a common antigen (Prinz, J. et al., Eur. J. Immunol. (1999) 29(10): 3360-3368, “Selection of Conserved TCR VDJ Rearrangements in Chronic Psoriatic Plaques Indicates a Common Antigen in Psoriasis Vulgaris”) and/or to specific VDJ rearrangements (Tamaru, J. et al., Blood (1994) 84(3): 708-715, “Hodgkin's Disease with a B-cell Phenotype Often Shows a VDJ Rearrangement and Somatic Mutations in the VH Genes”). What is needed is a better method for evaluating changes in human immune response cells and associating those changes with specific diseases.